1. Field of the Invention
The present invention relates generally to a multiprocessor system, and more particularly, but without limitation, to a direct access boot utility in a multipath architecture.
2. Description of the Related Art
Some electronic instruments, such as portable multimedia players (PMPs), handheld phones (HHPs), and personal digital assistants (PDAs) include multiple processors within one system to achieve high-speed operation. In such a system, a semiconductor memory device must be adapted for multiprocessor access. For example, the memory device may have multiple access ports, and it may be required to simultaneously input/output data through the multiple access ports.
One type of semiconductor memory device having two access ports is called a dual-port memory. A known dual-port memory used for image processing applications includes a random access memory (RAM) port accessible in a random sequence and a sequential access memory (SAM) port accessible only in a serial sequence. Dual-port memory has limited application, however.
A Dynamic Random Access Memory (DRAM) that does not employ an SAM port, and for which a shared memory area is accessible by processors through multiple access ports, is called herein a multiport semiconductor memory device or multipath-accessible semiconductor memory device to distinguish from the dual-port memory. An example of a conventional art multiport semiconductor memory is disclosed in U.S. Publication No. 2003/0093628. As disclosed therein, a memory array is constructed of first, second and third portions. The first portion of the memory array is accessed only by a first processor, the second portion is accessed only by a second processor, and the third portion is a shared memory area accessed by the first and the second processors. Some known multiprocessor systems include a multiport DRAM memory device and a single flash memory device.
Multiprocessor systems present many technical challenges, however. One such issue is multiprocessor access to a single flash memory device, for example, to quickly obtain boot code in each of the multiple processors. For this and other reasons, improved multiprocessor architectures are needed.